Pneumatic hammer



April 28, 19,25;A i l '1,535,599

G, H. GILMAN PNEUMATIG HAMMER Filed Sept. 30,-1918 2 Shets-Sheet 1 Patented A pr. 28 1925.-

uNiTED sTATEs PATENT OFFICE;

GEORGE n. G1LMAN,oF CLAREMoNT, NEW-HAMPSHIRE, Assr'eNoR lTo SULLIVAN MACHINERY COMPANY, A CORPORATION or MASSACHUSETTS.

- 'i Application `led September 30, 1918.V Serial No. 256,330. l

This invention relates to pneumatic hammers and more. particularly to the pneumatic y hammers used in drill Sharpeners for operating the upper swaging die, the object of the ,present invention being to provide means,

operably attached to the fluid pressure controlling lever. for holding the valvemechanism in an adJusted position to permit a fiow of Huid pressure to one end of the piston to vdifferential valvel. and its bushing.

hold the hammer-,in elevated position, and means for preventing the pressure fluid, which leaks slowly by the moving parts,l from accumulatingon the opposite end of the piston and so neutralizing the pressure acting on the first end.

In the manufacture of pneumatic hammersI` a clearance of about tliree-thousandtlis of an inch is allowed between the piston and cylinder. and a clearance of about one and one-half thousandths of an inch between the During the normal operation of the hammer the piston and valve reciprocate so rapidly that leakage does not occur, or if it does, it is so small as not to materially affect the operai. tion of the hammer. However, when the differential valve is held in an extreme position to permit a flow of pressure fluidto one end of the piston, the leakage past the moving parts accumulates on the other end of the piston and counterbalances the fluid pressure tending to hold the piston to one end of its cylinder, and the piston drops under the action of the force of gravity.

'This defect I overcome in my present iny vention which willbe best understood by to the-accompanying drawings of one illusreference to the following specification. and

trativ'e embodiment thereof` while its scope will be more particularly pointed out in the appended claims. i

In the drawings,-

Fig. 1 is a front elevation ofa drill sharp? ener embodying"my invention.

Fig. 2 is a ,longitudinal sectional view of the pneumatic hammer and its valve chambel'. .f

Fig. 3 is a view similartoFig. 2, but showing parts in a different position.

Fig. 4 1s a transverse section on 'the line 4 4 of Fig. 3.

sake of illustration, there is'shownl one vembodiment of the invention in a drill sharpener having a base 2 on which is secured a lower swaging die 3. Bolted to the base at 4 is an upright support 5 for supporting in y a vertical position a. pneumatic hammer 6 for operating an upper swaging block or die '7. The upper swaging block reciprocates in a vertical guide V8 formed integral with the support 5. Y

A foot lever 9 is attached to one end of a rocker shaft 10 passing through the hase 2, shaft carrying a lever 11 for actuating a vertically disposed rod 12 which controls the valve mechanism in a manner to be hereinafter described. A spring 13 is held under compression between a fiange on the support 5 and a collar on the valvercontrol rod, tonormally hold the rod in an elevated position.

The upper swaging die is reciprocated by a piston rod 14 carried on the lower end of a piston 15, of usual construction, the same the other end of. the rocker comprising a spooled center 16 around which `member 21 carried in the upper end of the cylinder.

This valve member carries a resilient packing and cushioning ring 22 in an annu lar recess 23, the edge of the packing projectinglslightly below the recess so that the beveled edge of the projection 20 will contact with the ring when the piston is inits extreme raised position. A valve 24 having intercommunicating longitudinal and transverse passages', is held seated against a shoulder formed in the member 21, so that it projects slightly into the recess, by a screw plug and coiled spring, as is clearly shown. It will further be noted that thev valvel is so constructed that the pressure in the uppei end of the cylinder is transmitted to the top surface of the valve and accordingly will maintain the same closed, thereby preventing leakage during operation of the motor.

A yoke 25 passes over the valve member and is provided with holes through which pass bolts 26 which are commonly used in hammers of this type to retain a tapered sleeve 27 on the lower end `of the hammer. Nuts are threaded onto the ends of the bolts into contact with the yoke and serve to retain the valve member 21 securely in place.

The differential piston valve mechanism and passages leading therefrom, as herein shown, are essentially the same as in the rock drill covered by Letters Patent No,

1,164,496, granted me .December 14, 1915,

and as that construction is now very com-l mon it is thought that an extended descript-ion of the parts and their action is not necessary. Pressure Huid is conducted to the inlet opening 28 through a pipe 20, flows alternately to the ends of the cylinder through passages 30, and leaves the cylinder by way ofthese same passages 30 and exhaust passages 81, leading to the atmosphere at 32. An opening 33 connects the cylinder at its center with the exhaust passages. Annular grooves 34 formed in the cylinder wall are connected by small passages to the ends of the valve chamber and serve to conduct the pressure fluid to one end of the differential valve and exhaust the fluid under pressure from the other end of the differential valve. Stops 35 are fastened in the ends of the valve chamber to limit the motion of the valve.

One of these stops is provided with a stepped bore to receive a valve actuating pin 36 carrying a collar 37 which slides in and has a close fit with the larger bore of thekstop. This collar serves as a guide for the pin 36 and also 'to check fluid pressure leakage because of its close fit in the cylinder and because the beveled head 37 bears against a shoulder on the stop when the pin is forced against it. The pin projects beyond the collar in both directions, the upper end passing through the smaller bore in the stop and contacting with the valve to force it to its extreme raised position, the lower and longer portion of the pin resting in a hole or depression 38 in a lever 39 attached to a rock shaft 40 operated by a lever 39 which is connected to the valve carrying the valve #eat and the second a perforated bridge 44 which acts as a stop or abutment for the valve plunger 45 and as an abutment for the spring 46 which acts on and tends to force the valve to its seat.

The means for operating this valve consists of a bell crank lever 47 pivoted on a holt 4S fastened to the frame support and connected to the valve actuating rod 12 by a link 4f). The coiled spring 13 acting on the valve actuating rod tends to raise the differential piston and close the exhaust valve 42 so that normally the pneumatic hammer is held in a raised position. y

When the operator desires to use the swaging mechanism he depresses the foot lever which actuates the valve control meehanism, and so opens the exhaust port 32 and frees the differential valve that the piston and valve can reciprocate and perform their usual function. When the piston travels upward it traps air in the recess and compresses it, thus forming a cushion which absorbs the inertiaot the piston and gives the piston a start downward. This cushion of air further serves to keep the piston from contacting with the valvei24 which remains closed during the usual operation of the hammer.

VVhen'the operator removes his foot from the lever 9, the control rod 12 is forced upward and so closes the exhaust port and raisesthe differential valve to permit a flo-v of fluid pressure to the lower end of the piston. The piston moves rapidly upward and compresses the air trapped in the recess until it contacts with the small valve 24 which it raises, thus exhausting the entrapped air and permitting the piston to seat on the cushion ring 22.. If the pressure fluid that leaks by the piston rings and diferential valve flows past the'projection 2O and the resilient ring 22 it is exhausted to the atmosphere and so cannot accumulate and counterbalance the pressure acting on the lower side of the piston. Valve 42 closes the exhaust port so that, as the air leakage in the di'erent parts goes on, the pressure in the different passages will slowly be built up to the inlet pressure and the leakage will stop. This results in a saving in pressure fluid consumption when the drill Sharpener is not in operation.A Thus it is seen that l have devised a simple and effective means for normally retaining the upper swaging die in an elevated position and for preventing a loss ofpressure fluid when the swaging mechanism is not in operation.v

While I have herein shown and described for the purpose 'of illustration one specific form of the invention, it is to be understood that the same has been chosen for illustrative purposes only and that extensive deviations maybe made from the disclosed form thereof without departing from the spirit of the invention.

. W'hat I claim is new and desire to lsecure by Letters Patent is: i

1. In a drill Sharpener, the combination' with aswaging die, a piston for actuating said die,4 and -fluid distribution vmeans for pressure to the opposite sides thereof and- -for exhausting the fluid 'including a normally open exhaust means, of means "for holding said piston inoperative including means for subjecting it to unequal pressures on opposite sides, and means distinct from said'first mentioned exhaust-means for preventing equalization of the pressures on the opposite sides of said piston.

'2. Inra drill sharpener, the combination with a swaging die normally biased toward the work, of controlling means therefor comprising means for raising the die including a cylinder having a piston therein and means for supplying Yfluid pressure to the space at one end of the piston and exhaustit from the other, and means for holding said pistonin raised position including auxiliary exhaust means.

3. In a drill Sharpener, a hammer operative to hammer a Work piece, fluid pressure means mcludmg a cylinder and piston for.

operating said hammer and including fluid supply and `exhaust means operative to es- V'tablish a Vpressure at one` side of the piston 'to move the hammer from the work piece and to vent the oppositeside of -the piston to prevent fluid resistance to such movement,

and separate means for exhausting fluid pressure operative-When the piston reaches the limit of itstravel away from the Work piece;

4. In a drill Sharpener, a pneumatic hammer including means fory supplying and exhausting fluidl during the operation thereof..and separate means operative only When said hammer is idle exhausting such part of the fluid pressure therefromas leaks past the piston When the latter is stationary.

.5. In aj drillsharpener, a pneumatic hammer, lfluid pressure'means including a -piston for operatingl said hammer, and means actuated bythe piston andclosed exceptwhen v so actuated for exhausting part of the fluid pressure from said fluid pressure means.

,6. In av drill Sharpener, a pneumatic hammer comprising cylinder and piston elements cooperatmg to form chambers to which fluid vis supplied and from which fluid is exhausted in alternation during operationof said hammer, fluid pressure controlling means includingA exhaust controlling means for controlling the operationof said hammer,y and means independent of said first named means for exhausting fluid from one of said chambers after said exhaust controllingc mechanism is closed.

7. In a drill Sharpener, a pneumatic ham- .mer having an exhaust passage, fluid pres-f sure means including exhaust controlling mechanism for operatmg said hammer, and means independent of gs ald first named means and inoperative duringI operation of said'hannner for exhaust-ing fluid pressure therefrom.

8. In a drill Sharpener, a pneumatic ham- -mer, fluid pressure means for operating said pneumatic hammer, and means forexhausting-fluid pressure from said hammer, said lastnamed means being inoperative during vthe operation of said hammer.

9. In a drill Sharpener, acylinder, a piston therein, means including an automatically operated valve for causing said vpiston to move repeatedly over a limited paath in said cylinder during operation of the drill Sharpener, and means operative to cause movement of the piston beyond the limits of its normal path at a time when the drill sharpener is not in operation.

10. In a drill Sharpener, a' piston, means for moving said piston to operatethe drill sharpener, cushioning means to limit the upward movement of said piston, and means for rendering said cushioning means inoperative Whensaid drill Sharpener is not in operation.

11. In a drilll Sharpener, the combination comprising svvaging means, fluid pressure means including an inlet, and a plurality of outlets connnunicating with one end of -said fluid pressure means for operating said swaging means. certain of said outletsl being closed when said sivaging means is not in operation.

, 12. In a drill Sharpener, the combination comprising swaging means, fluid pressure means including an inlet, and a plurality of outlets for operatingsaid swaging means, certain of said outlets being closed in all positionsL` of the piston when said swaging means is-operative.

13. In a pneumatic hammerl, a cylinder', an exhaust passage, a valve to direct pressure fluid to one end of the cylinder', an auxiliary valve controlling said exhaust passage, and means to prevent equalization of pressure in the opposite end of the cylinder when said auxiliary valve is closed.

:14. In a pneumatic hammer, a cylinder. a. pressure fluid inlet and' an outlet, valve means for controllingsaid inlet and outlet` separate valve means for .controlling said outlet, and interconnected means for controlling the valve means.

15. In a pneumatic hammer, a piston, a cylinder, fluid pressure means for forcing said piston toward one end of said cylinder including passages leading to each end of the cylinder, supply and exhaust means, and means for connecting .one end' of the cylinder'to, said supply and `theother end to said exhaust means, means for closingL said exhaust means, Iand means for preventing fluid 16. In a pneumatic hammer', a cylinder, a piston therein, means for supplying fluid pressure to one end of the cylinder and exhausting it from the other end, means for closing said exhaust means, and means for preventing fluid pressure'accumulations at the end of th'e'cylinder which last communicated with said closed exhaust means before the closure of the latter. v

17. In a drill sliarpener, an anvil die, a movable die adapted to cooperate therewith andhaving a normal bias towards said anvil die, means for reciprocating said movable die relative to said stationary die comprising apneumatic motor, which comprises cylinder, and piston members and fluid distributing mechanism including fluid supply and exhaust means, a valve and passage means for alternately supplying and exhausting fluid to cause opposite movements of oneof said members relative to the other, and a connection between said movable die and said movable member, means formoving saidvalve to a position to cause said movable member to retract the movablediefrom the anvil die, means for closing Athe exhaust means, Vand means includingf auxiliary exhaust means for preventing fluid leakagel causing 4'opposite movement of the movable memberand die.v

18. In a pneumatic hammer, a cylinder, a

- piston having a normal bias toward oneend of the cylinder, a fluid supply connection,`

exhaust connection, and means for maintaining said piston at the end of the cylinder opposite-the end first mentioned when said separate exhaust connection is lclosed including means for maintaining unequal pressures at opposite ends of the cylinder.

20. In a pneumatic hammer, a cylinder, a

piston having anormal bias toward one end of the cylinder, a fluid supply connection, distributing ports for the cylinder, a main exhaust connection for the cylinder, a distributing valve,'a separate valve for, said exhaust connection, and means-'for maintaining said piston at the end of the cylinder opposite the end first mentioned when said separate exhaust connection controlling valve is closed including means for mainpressure on said last menof' a fluid pressure in said last mentioned end including a valve automatically opened upon movement of the piston to said inoperative position.

22. In a pneumatic hammer, a cylinder, a

piston having a normal bias toward one end of the cylinder, a fluid supply' connection, distributing ports for said cylinder, a main exhaust connection for said cylinder, a distributing valve, a Separate valve for'said exhaust connection, and meansfor maintainin'g said piston inoperative at the end of the cylinder opposite the first mentioned end when said separate exhaust connection controlling valve is closed, said means including a valved connection' With the atmosphere adapted to be opened by impact of the-'piston on the valve upon 'movement' to said inoperative position.

' 23. In a pneumaic cylinder, a piston re l mon supply and exhaust passages' leading to each end of said' cylinder, a; distributing valve controlling said passages,- supply and exhaust connections alternately connectible by saidcvalve to said passages, a-stopvalve controlling said exhaust connection, means operative to move said 4distributing valveto connect the upper end of said 'cylinder' to exhaust and the lower end to supply, means for closing said stop valve, and means for preventing equalization of pressures on opposite sides of the piston by leakageafter closure of said stop valve.- 24'. Ina pneumatic:hammer, a vvert-ical cylinder, 'a piston -reciprocable therein, means including distribution ports for automatically effecting supply -of pressure fluid and its exhaust in alternation to the opposite ends of the cylinder,` means operative to limit the` supply of pressure fluid to the ports leading to the lower end of the cylinder, means operative to prevent discharge from the port leading to the upper end of the cylinder, and means operative to pre-l vent the lpressure lleaking past the-piston from the lower to theupper. Side thereof from acting onthe upper end ofthe piston. In testimony whereof Iv affix my signature.

GEORGE H.r GILMAN.

hammer, a vertical iprocable therein, coin'- i' 

